1. Field of the Invention
The present invention relates to a plasma display panel, and more particularly, to a method of driving a plasma display panel, and an apparatus thereof enabling to manage a digital signal properly.
2. Background of the Related Art
Generally, a plasma display panel (hereinafter abbreviated PDP) is a display device that displays a picture by effecting luminescence of phosphors by ultraviolet (UV) rays generated from the discharge of a gas. Such a PDP has the advantage that it can be easily formed into a thin film and large-sized, and, compared to the conventional Cathode Ray Tube: (CRT), it can provide a greatly improved picture quality.
As shown in FIG. 1, a discharge cell of PDP includes scan and sustain electrodes 30Y and a common sustain electrode 30Z formed in parallel with each other under a front substrate 10 and an address electrode formed on a back substrate 18. In this case, each scan and sustain electrodes 30Y and the common sustain electrode 30Z are composed of transparent electrodes 12Y, 12Z and metal bus electrodes 13Y, 13Z which are narrower than the transparent electrodes 12Y, 12Z. This transparent electrodes 12Y, 12Z are formed with Indium-Tin-Oxide (ITO), and the metal bus electrodes 13Y, 13Z are formed with Cr to reduce a drop of electric pressure by the highly resistant transparent electrodes 12Y, 12Z.
Also, on the front substrate 10 are laminated a front dielectric layer 14 and a protective layer 16. On the front dielectric layer 14 is accumulated wall charge generated during plasma discharge. The protective layer 16 prevents the front dielectric layer 14 from being damaged by the plasma discharge, and heightens the emission efficiency of secondary electrons. A magnesium oxide (MgO) is typically used for the protective layer 16.
A back dielectric layer 22 and barrier ribs 24 are formed on the back substrate 18, where an address electrode 20X is formed, and a phosphor 26 is coated on the surfaces of the address electron 20X and the barrier ribs 24. The address electrode 20X is formed in an intersectional direction of the scan and sustain electrode 30Y and the common sustain electrode 30Z. The barrier ribs 24 are formed in parallel with the address electrode 20X to prevent ultraviolet and visible rays from leaking in an adjacent discharge cell. The phosphors 26 become excited by the ultraviolet rays generated from plasma discharge so as to irradiate one of red, green, and blue visible rays.
Such a PDP divides a single frame into many sub-fields in order to display a gray scale of a picture. And, each sub-field is divided into a reset period to generate electric discharge equally, an address period to choose a discharge cell, and a sustain period to enable to change the gray scale of the picture according to the frequency of electric discharge.
During the address period, scan pulses are applied to the scan and sustain electrodes 30Y and data pulses synchronized with the scan pulse is applied to the address electrode 20X. At this time, an address discharge is generated from discharge cells to which the scan and data pulses are applied. And, after scan pulses are applied to both of the scan and sustain electrodes 30Y, a sustain pulse is applied to scan and sustain electrodes 30Y and the common sustain electrode 30Z alternately. After that, a sustain discharge is generated in discharge cells from which the address discharge has been generated.
In case that a picture is displayed with 256 gray scales, a frame duration (16.67 ms) corresponding to 1/60 second is separated into eight sub-fields. The reset and address periods of each sub-field are the same in each sub-field, and, on the contrary, the sustain period increases in the ratio of 2n (n=0, 1, 2, 3, 4, 5, 6, 7, 8.) Thus, sustain periods in each sub-field changes so as to realize the gray scale of a picture.
FIG. 2 illustrates the apparatus for driving a plasma display panel. As shown in FIG. 2, the apparatus for driving a plasma display panel is composed of a video signal unit 32, a video scan converter (VSC) 34 and a PDP driving unit 36.
The video signal unit 32 inputs an analog signal included a video signal and adjusts the level of voltage and gains so as to control brightness and contrast of a picture according to the control of a user.
The video scan converter 34 converges an analog signal inputted from the video signal unit 32 according to the resolution of PDP. At this time, the analog signal is changed to digital signal and is inputted into the driving unit 36.
And, the PDP driving unit 36 revises the digital signal inputted from the video scan converter 34, and supplies the PDP with the revised digital signal.
The conventional PDP driving device can only display images corresponding to analog signal but can't display images corresponding to the digital signal. Even if a digital and an analog converter is equipped to display images corresponding to digital signal the resolution of PDP is deteriorated by perversion and reduction generated in the transformation process of digital to analog to digital signal.